Complete Avulsion of the Hoof Capsule and Subsequent Testicular Degeneration in a Criollo Stallion

Background: Complete avulsion of the hoof in horses, also known as exungulation, is not a commonly reported injury and usually leads to euthanasia due to the great amount of tissue loss, intense pain, secondary complications, expensive and lengthy treatment. It can involve deep structures and cause different complications leading to chronic lameness. In stallions affected by such injury, the reproductive tract and performance may also be affected. The aim of this study was to report a case of complete avulsion of the right front hoof in a Criollo stallion and subsequent bilateral testicular degeneration.Case: A 10-year-old Criollo stallion was referred to the Veterinary Clinical Hospital of the Federal University of Pelotas (HCV- UFPel) with a complete avulsion of the left front hoof. At admission, the stallion had clinical parameters compatible with intense pain and blood loss. Evaluation of the wound demonstrated that the distal end of the third phalanx (P3) was exposed but no fracture was detected on radiological evaluation. No other structure was apparently affected. Initially, anti-inflammatory (phenylbutazone) and opioid (morphine) was given for pain control and supportive fluid therapy was started to restore hydration. Antibiotic (Sulfamethoxazole with trimethoprim) were administered for 10 days. Continued therapy with phenylbutazone, pentoxifylline, omeprazole and supplementation with methionine, biotin and zinc was also given. Local treatment was carried out by cleaning the wound, applying an antimicrobial ointment and dressing it with a bandage. Wound management was adapted according to the evolution and healing process. The stallion was kept in stall rest during its hospitalization time. In the second month after the injury, accumulation of liquid in the scrotum was observed. Clinical and ultrasound evaluation lead to a presumptive diagnosis of testicular degeneration. The stallion was discharged after three months when the wound was almost healed and the hoof had started to grow. Six month later, a follow up by the referring vet showed that the hoof was almost completely grown and the x-ray assessment demonstrated a cranial rotation and resorption of the distal end of the third phalanx.Discussion: The stallion of this report had a complete avulsion of the hoof capsule caused by trauma. Conservative treatment was established including wound cleaning and dressing to avoid contamination, control of pain and inflammation, antimicrobial care and supplementation to support hoof growth. Time period for wound healing and hoof growth was in agreement with other cases described previously. Bone sequestrum of the distal end of the third phalanx, and detachment of a fragment were observed in this case, followed by bone resorption. The stallion was closely monitored to prevent laminitis in the contralateral limb and no alterations were detected during the treatment period. Testicular degeneration was observed, probably caused as a consequence of hoof avulsion and due to a long period of stall rest. Degenerative alterations in testicles interfere with thermoregulation and spermatogenesis, affecting semen quality and reproductive performance. Rotation of the third phalanx was also observed six months later caused by the hoof loss. In conclusion, the patient of this report had a complete regrowth of the hoof capsule although a long intensive treatment was necessary to achieve this result. As a consequence, testicles degeneration may happen impairing its function as a stallion.Keywords: exungulation,hoof trauma, degenerative changes.